Reproductive Genetics 3 Flashcards

Describe the risks for aneuplodiy or single gene disorders for patients based on age, prior history, or screening results.

1
Q

What is confined placental mosaicism?

A
  • Found in approximately 1% of CVS samples
  • Confirmed in fetus in 23% of cases
  • Amniocentesis often recommended
  • CPM may be associated with IUGR
  • Trisomy 17 will always indicate CPM
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2
Q

What is spinal muscular atrophy (SMA)?

A
  • Autosomal recessive progressive neurodegenerative disorder
    • lower motor neurons in anterior horn of spinal cord
  • Symmetric proximal msucle weakness
    • progresses to hypotonia and respiratory failure at age 2
  • Most common form of a result of homozygous absence of functional SMN1 gene
  • Incidence is 1 in 6000
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3
Q

Describe the risks of osme of the common aneuploidies in liveborn babies.

A
  • Trisomy 21 (Down syndrome) - 1 in 700
  • Trisomy 18 (Edward syndrome) - 1 in 3000
  • Trisomy 13 (Patau syndrome) - 1 in 5000
  • 45, X (Turner syndrome) - 1 in 2500 females and 600 males
  • 47,XXY (Klinefelter syndrome) - similar to Turner
  • 47, XYY and 47, XXX - 1 in 1500
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4
Q

What fetal chromosome abnormality does not increase with maternal age?

A

Polyploidies or microdeletions

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5
Q

What is the risk for recurrence in aneuploidy?

A
  • If women have miscarriages that are due to chromosome abnormality the first time around, the second one will have an increased risk of aneuploidy
  • Risk is much lower for someone who is a carrier, not 33%
    • most aneuploidy pregnancies spontaneously miscarry
  • Risk is much higher if the mother is the carrier of the translocation versus the father
    • sperm carrying extra chromosomes aren’t as able to fertilize the eggs
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